Test cases for tool-using agents in Agentic AI

Introduction

Test cases help check if tool-using agents work correctly. They make sure the agent uses tools as expected.

When you want to verify an agent can call external tools properly.

When you need to check if the agent handles tool errors gracefully.

When you want to confirm the agent follows the right steps using tools.

When updating or improving the agent's tool usage abilities.

When debugging why an agent's tool use is not giving correct results.

Syntax

Agentic AI

def test_agent_tool_usage(agent, tool_input, expected_output):
    result = agent.use_tool(tool_input)
    assert result == expected_output, f"Expected {expected_output}, got {result}"

This is a simple test function to check tool usage.

Use assertions to compare expected and actual results.

Examples

Test if the agent returns the expected weather info when using a search tool.

Agentic AI

def test_agent_can_search(agent):
    query = "weather today"
    expected = "Sunny"
    result = agent.use_tool(query)
    assert result == expected

Test if the agent raises an error when given bad input to a tool.

Agentic AI

def test_agent_handles_tool_error(agent):
    bad_input = ""
    try:
        agent.use_tool(bad_input)
    except ValueError:
        pass
    else:
        assert False, "Agent did not raise error on bad input"

Sample Model

This program defines a simple agent that uses a tool to get weather info. It tests correct output and error handling.

Agentic AI

class SimpleAgent:
    def use_tool(self, input_text):
        if not input_text:
            raise ValueError("Input cannot be empty")
        if input_text == "weather today":
            return "Sunny"
        return "Unknown"

def test_agent_tool_usage():
    agent = SimpleAgent()
    # Test correct tool usage
    assert agent.use_tool("weather today") == "Sunny"
    # Test error handling
    try:
        agent.use_tool("")
    except ValueError as e:
        print(f"Caught error: {e}")
    else:
        print("Error not caught")

if __name__ == "__main__":
    test_agent_tool_usage()

Important Notes

Always test both normal and error cases for tool-using agents.

Use clear, simple inputs and expected outputs in tests.

Run tests often to catch bugs early.

Summary

Test cases check if agents use tools correctly and handle errors.

Write tests with expected inputs and outputs.

Testing helps keep agents reliable and easy to improve.

Practice

1. What is the main purpose of writing test cases for tool-using agents?

easy

A. To add more tools to the agent

B. To make agents run faster

C. To check if agents use tools correctly and handle errors

D. To reduce the size of the agent's code

Solution

1. Step 1: Understand the role of test cases

   Test cases are designed to verify that the agent behaves as expected, especially when using tools.

2. Step 2: Identify the main goal for tool-using agents

   For agents that use tools, tests ensure they use these tools correctly and handle any errors gracefully.

3. Final Answer:

   To check if agents use tools correctly and handle errors -> Option C

4. Quick Check:

   Test cases purpose = check tool use and errors [OK]

Hint: Test cases verify correct tool use and error handling [OK]

Common Mistakes:

• Thinking test cases speed up agents
• Believing test cases reduce code size
• Assuming test cases add tools

2. Which of the following is the correct way to write a test case for a tool-using agent in Python?

easy

A. test agent tool: assert agent.use_tool('calculator', '2+2') == 4

B. def test_agent_tool(): assert agent.use_tool('calculator', '2+2') == 4

C. def test_agent_tool: assert agent.use_tool('calculator', '2+2') == 4

D. def test_agent_tool() assert agent.use_tool('calculator', '2+2') == 4

Solution

1. Step 1: Check Python function syntax

   Python test functions start with 'def', have parentheses, and a colon at the end.

2. Step 2: Verify assertion syntax

   The assert statement must be inside the function and correctly compare expected output.

3. Final Answer:

   def test_agent_tool(): assert agent.use_tool('calculator', '2+2') == 4 -> Option B

4. Quick Check:

   Correct Python test function syntax = def test_agent_tool(): assert agent.use_tool('calculator', '2+2') == 4 [OK]

Hint: Remember Python functions need parentheses and colon [OK]

Common Mistakes:

• Omitting parentheses in function definition
• Missing colon after function header
• Incorrect assert statement placement

3. Given this test case code snippet, what will be the output if the agent returns 5 instead of 4?

def test_agent_tool():
    result = agent.use_tool('calculator', '2+2')
    assert result == 4
    print('Test passed')

medium

A. Test passed

B. SyntaxError

C. No output

D. AssertionError

Solution

1. Step 1: Understand assert behavior

   If the assert condition is false, Python raises an AssertionError and stops execution.

2. Step 2: Check the test condition

   The test expects result == 4, but agent returns 5, so assert fails.

3. Final Answer:

   AssertionError -> Option D

4. Quick Check:

   Assert fails if values differ = AssertionError [OK]

Hint: Assert fails if expected and actual differ [OK]

Common Mistakes:

• Thinking print runs after failed assert
• Confusing AssertionError with SyntaxError
• Assuming no output on failure

4. Identify the error in this test case for a tool-using agent:

def test_agent_tool():
    result = agent.use_tool('search', 'weather today')
    assert result = 'sunny'
    print('Test passed')

medium

A. Using '=' instead of '==' in assert

B. Missing parentheses in print

C. Wrong function name

D. Agent tool name is invalid

Solution

1. Step 1: Check assert statement syntax

   In Python, '=' is for assignment, '==' is for comparison. Assert needs '==' to compare values.

2. Step 2: Verify other parts

   Print has parentheses, function name is valid, and tool name is plausible.

3. Final Answer:

   Using '=' instead of '==' in assert -> Option A

4. Quick Check:

   Assert needs '==' for comparison [OK]

Hint: Assert compares with '==', not '=' [OK]

Common Mistakes:

• Confusing assignment '=' with comparison '=='
• Ignoring syntax errors in assert
• Assuming print needs no parentheses

5. You want to test an agent that uses a calculator tool to handle multiple expressions. Which test case best checks if the agent correctly handles both valid and invalid inputs?

hard

A. def test_calc(): assert agent.use_tool('calculator', '3*3') == 9; assert agent.use_tool('calculator', 'abc') == 'error'

B. def test_calc(): assert agent.use_tool('calculator', '3*3') == 9; assert agent.use_tool('calculator', '3/0') == 0

C. def test_calc(): assert agent.use_tool('calculator', '3*3') == 9; assert agent.use_tool('calculator', '') == ''

D. def test_calc(): assert agent.use_tool('calculator', '3*3') == 9; assert agent.use_tool('calculator', null) == null"

Solution

1. Step 1: Check valid input test

   All options test '3*3' == 9 correctly, which is good for valid input.

2. Step 2: Check invalid input handling

   def test_calc(): assert agent.use_tool('calculator', '3*3') == 9; assert agent.use_tool('calculator', 'abc') == 'error' expects 'abc' input to return 'error', which correctly tests error handling. Others expect incorrect or unclear outputs.

3. Final Answer:

   def test_calc(): assert agent.use_tool('calculator', '3*3') == 9; assert agent.use_tool('calculator', 'abc') == 'error' -> Option A

4. Quick Check:

   Test valid and invalid inputs properly = def test_calc(): assert agent.use_tool('calculator', '3*3') == 9; assert agent.use_tool('calculator', 'abc') == 'error' [OK]

Hint: Test both valid and invalid inputs explicitly [OK]

Common Mistakes:

• Expecting wrong output for invalid input
• Not testing error cases
• Assuming empty or null inputs return themselves